I believe that our current behaviour of treating all embedded elements in effect as inlines, and replacing them by U+FFFC OBJECT REPLACEMENT CHARACTER for purposes of bidi resolution, was just an oversight.
Note that implementing this will require being able to break a block element into multiple paragraphs for Bidi resolution, which makes it similar to bug 263359.
Created attachment 437306 [details]
Created attachment 437307 [details]
Reference for testcase
This is also tested in the fourth test of:
This was fixed by bug 263359, and the testcase is effectively equivalent to layout/reftests/bidi/613157-1.html
http://test.csswg.org/suites/css2.1/20101001/xhtml1/bidi-breaking-001.xht is 404, but we pass http://test.csswg.org/suites/css2.1/20101210/html4/bidi-breaking-001.htm, if that's the same thing.